I have 423 frames in my animated squencer . When i try to render it start dark then going normal like after few frames after that around 160-165 frames its going dark ,around 180-185 frames its coming back again .I checked light if i accidentally put a frame for light effect but its all clean .Its not a full black screen render .I mean like its going darker every frame until go for fully dark then its coming back from fully dark to normal ,frame by frame